The Supreme Court has decided to take up cases involving California's Proposition 8, which bans gay marriage, and a provision of the federal Defense of Marriage Act. The justices' rulings on the cases are likely to be announced next June, after arguments are heard in the spring. Advocates on both sides of the issue were welcoming the news.

While a ruling on the 1996 federal measure's constitutionality was anticipated, the decision to take up Proposition 8, which voters approved in 2008, was not — as NPR's Nina Totenberg reports for All Things Considered:

"Defying most expectations, the justices said they will examine two cases, presenting the possibility that the court could decide all the issues surrounding same-sex marriage in one fell swoop."

The Associated Press reports the case regarding California's ban on same-sex marriage "could give the justices the chance to rule on whether gay Americans have the same constitutional right to marry as heterosexuals."

As Nina reported in October, the Defense of Marriage Act "defines marriage as being only between a man and a woman, meaning that the federal government is barred from recognizing same-sex marriages even when they are legal and recognized by state law."

With regards to DOMA, the AP says the court will decide "whether Congress can deprive legally married gay couples of federal benefits otherwise available to married people." It adds:

"A provision of the federal Defense of Marriage Act limits a range of health and pension benefits, as well as favorable tax treatment, to heterosexual couples."

In its live blog covering today's announcement, the SCOTUSBlog reports, "The Court has offered to rule on Prop. 8 and on DOMA Section 3, but it also has given itself a way not to decide either case." As NPR's Cathy Shaw explains, the court could say that "the people bringing the case have no standing, or no right to be in court at all."

Update at 5:50 p.m. ET. Reactions To Review:

After the court announced its decision to review the two cases late this afternoon, advocates on both sides of the gay marriage issue said they see an opportunity to settle the matter in their favor.

Marriage Equality USA executive director Brian Silva welcomed the news, noting the momentum that included three states approving same-sex marriage by popular vote last month, along with court victories earlier in 2012.

"The Supreme Court is taking up these marriage equality cases in what has already been a historic year for the freedom to marry," Silva said in a news release.

The conservative National Organization for Marriage also praised the court's acceptance of the cases, especially the one concerning Proposition 8, which the group helped to get on the California ballot.

"Had the Supreme Court agreed with the lower courts' decisions invalidating Proposition 8, it could simply have declined to grant certiorari in the case," NOM chairman John Eastmansaid today. "It's a strong signal that the justices are concerned with the rogue rulings that have come out of San Francisco at both the trial court and appellate levels."

Update at 4:35 p.m. ET. Rulings May Be Limited:

The possibility that the court could hear two cases without deciding them may seem unusual to anyone who doesn't closely track the goings-on of the nation's highest court. But at least a partial explanation is that the Supreme Court might confine itself to considering jurisdiction in the cases, rather than the merits of the claims.

In their court order accepting the Defense of Marriage Act case, the justices agreed to determine "whether the Executive Branch's agreement with the court below that DOMA is unconstitutional deprives this Court of jurisdiction to decide this case; and whether the Bipartisan Legal Advisory Group of the United States House of Representatives has Article III standing in this case."

That order refers to Windsor v. U.S., a case in which a federal appeals court ruled in favor of the plaintiff, Edith Windsor, 83.

As Joel Rose reported in October, "The plaintiff... married her longtime partner in Canada in 2007. When her partner died two years later, Windsor was forced to pay more than $360,000 in federal estate taxes on her inheritance — taxes she would not have paid if the federal government recognized her marriage as valid."